HMS Lagos, photographed as completed, shows the 4in gun just abaft her funnel.
HMS Barfleur is shown as completed. Note the 4in gun abaft the funnel, intended solely to fire starshell. It was necessary because otherwise one of the 4.5in mounts would have been dedicated to this purpose. The 4in was selected after several alternative flare projectors had been rejected. This gun had no associated director, hence was not considered useful for any other purpose. This class introduced the Mk VI director, with its Type 275 radar capable of blind anti-aircraft fire. Barfleur has the standard late-war destroyer rig, with Type 293 on the lattice foremast and Type 291 (air warning) on a stub mainmast aft. The topmast carries her HF/DF array.
HMS Lagos, photographed on 28 December 1945, was a 1942 `Battle’ whose 4in gun had been replaced by two single Bofors abreast. Twin Bofors are visible on the amidships platform and on the after superstructure; the single mounts elsewhere are less visible.
The 1942 Fleet Destroyer (`Battle’ Class) DNO’s initial answer to the mid-1940 question of providing a dual-purpose gun for destroyers was quite unsatisfactory. He could increase the elevation of the usual single mount only to 55°. Unfortunately dive bombers typically dropped their bombs at just such an angle; to hit them the gun needed at least another 20° of deflection angle, for a minimum acceptable elevation limit of 75°. Periodically the possibility of the army’s 85° single mounting was raised, but it was always rejected as unsuited to a lively ship. The largest destroyer gun which could easily elevate to near-vertical angles was the 4in gun. It later became clear that DNO could modify the one truly dual-purpose mount firing a shell of roughly destroyer calibre, the twin between-decks 4.5in in an enclosed pillbox shield, which currently armed the new fleet carriers, the battlecruiser Renown and three rebuilt Queen Elizabeth class battleships. In these ships it fired fixed ammunition, while a destroyer would use separate shells and cartridge cases. The more serious problem was that the mount was quite heavy – which had not really mattered in the capital ships then carrying it.
From the Norwegian campaign (April-June 1940) on there was considerable interest in an all-dual-purpose destroyer battery. DTSD formalised it by stating, on 21 October, that Staff Requirements should require that all future long-range guns for destroyers and smaller ships be dual-purpose. He noted that all modern US destroyers had fully dual-purpose main batteries (their British detractors claimed that they were top-heavy). War experience showed that four guns should fire ahead, and also that the very expensive 62pdr was not really needed (the extreme range it offered could not really be exploited). DTSD was therefore willing to accept even the 4in gun. He wanted at least two such weapons, with 85° elevation, effective fire control, and ship stabilisation (as in a `Hunt’ or a converted anti-aircraft destroyer). In addition DTSD wanted two heavy close-range mountings (pompoms or twin Hazemeyer Bofors) and four Oerlikons; to get so much he was willing to surrender remote power control of the main battery (but without such control, the heavier weapons would be far less effective). ACNS(W) rejected the 4in as not `man enough’ for a destroyer; he wanted a dual-purpose 4.7in gun elevating to 85°. Deputy Controller urged a decision soon enough for a new gun mounting to be available in time for the next new construction programme (1942).
As a preliminary to writing a Staff Requirement for the 1942 destroyer, the idea was discussed at a 9 April 1941 Deputy Controller’s meeting. Opinion did not unanimously favour the dual-purpose gun. DNC and DNO both advocated something like the `Tribal’, as it was then being rearmed, with six 4.7in and a twin 4in anti-aircraft gun. Director of Plans offered two possibilities, one with four single 62pdrs (one elevating to 85°, the others to 40°), and one with two twin low-angle 4.7in (50lbs) and one single high-angle gun. DTSD preferred the 4in `L’ class (four twin 4in). DTSD asked for sketches of all four alternatives, in each case with the two sets of quadruple torpedo tubes considered the minimum to have a good chance of hitting a fast freely-manoeuvring target (experience had also shown the value of having one mount trained on each beam at night). ACNS(H) rejected both Director of Plans’ concepts, one because it offered too little ahead fire (`we always chase and seldom stop our enemy’) and the other as overgunned. He thought that the greatest threat to destroyers and to the ships they escorted would be low-level air attack. He therefore preferred three twin 4.7in (40°) and four-cornered anti-aircraft fire (four twin Bofors), the extra light AA being paid for by eliminating one set of torpedo tubes.
Anti-aircraft fire was not the only controversial issue: ACNS(W) objected that too much was being sacrificed for a large torpedo battery, which would probably never be used, since with the advent of radar, surely classical night torpedo attacks were no longer possible. Furthermore, the rigid line of battle was obsolete; in future ships would fight in small flexible groups with greater freedom of manoeuvre, hence being bad torpedo targets. All of this proved quite premature. Moreover, like the US Navy, the British were apparently entirely unaware of Japanese torpedo tactics and capabilities, which would be demonstrated so dramatically in the South Pacific. As for the British, not long after ACNS(W) spoke, Home Fleet destroyers made night attacks on the German battleship Bismarck on 26 May 1941. The effort to drive them off, inescapable in view of the threat they represented, kept her fire-control crews awake and may have contributed substantially to their failure to deal with the heavy ships which sank her the next day. Other British destroyer torpedo attacks contributed substantially to sinking the Scharnhorst in 1943. The threat of torpedo attacks helped protect convoys both in the Mediterranean and in the Arctic from major enemy surface attackers, and near the end of the war a British destroyer flotilla torpedo attack sank the Japanese heavy cruiser Haguro. Postwar, the potential anti-raider role of the torpedo kept this weapon on board British destroyers.
As in the Emergency programme, operational endurance would drive up the size of the ship. DTSD wanted 4,000nm at 12-14kts. He suspected that alone would require something like a `J’-class hull. VCNS supported DTSD: for every day a destroyer fired at another ship she fired twenty times at aircraft. The existing 4in gun was not enough. He agreed with the ACNS(H) proposal for a four-cornered close-range anti-aircraft battery, using twin Bofors rather than pompoms, but also wanted at least six, and probably eight, Oerlikons. VCNS agreed with ACNS(W) that opinion was so divided that it would take a conference or perhaps a committee to decide the issue. Even so, on 14 May 1941 Controller felt comfortable asking DNC to sketch the ship VCNS implicitly supported, armed with four dual-purpose 4.7in guns (four twin 4in as alternative) and four-cornered close-range antiaircraft weapons. This was the beginning of the `Battle’ design.
To DNC, the only dual-purpose 4.7in gun on the table was a notional single 80° mounting, which weighed about as much as a twin 4in. Unfortunately each of the four Hazemeyers (twin Bofors) weighed about as much as a single 4.7in 40° mounting. DNC’s initial approach would have displaced 2,250 tons, which was too large for yards which typically built destroyers side by side. It was also too large for Controller. Cutting two of the twin Bofors and using more compact (modified `Tribal’ rather than `L’ class) machinery made it possible to reduce standard displacement to 2,000 tons, but that still seemed a bad bargain. DNC then suggested using a notional twin between-decks mounting whose weight he estimated on the basis of the twin 4.5in. He argued that to be practicable any high-angle destroyer mounting had to use a between-decks design, the crew and ammunition supply parties working under cover and the disability of very high trunnions being markedly reduced. DNC offered three gun mounts (one aft), fearing criticism that a ship at least as large as a `Tribal’ would have only half the battery. The three designs were submitted on 22 June 1941. Controller was impressed by the extent to which the Bofors mounts forced up the size of the ship, so he asked whether destroyers might be limited to Oerlikons only. Eliminating the Bofors in DNC’s six-gun ship would cut tonnage by 75 tons and increase speed by a knot.
Only DNC’s six-gun option approached what was wanted. Canvassing destroyer officers, Controller concluded that all of them wanted four main battery guns firing forward, at least some heavy HA guns, and plenty of Oerlikons. If 4.7in guns were wanted the ship would be expensive, with twins forward. The only acceptable cheap destroyer would be a super Emergency type with three twin 4in. A meeting on 11 July 1941 produced a set of draft Staff Requirements. Speed would not be less than 32kts deeply loaded, and endurance would be 7,000nm at 12kts `clean’ (as in an Intermediate); it was not clear that the 4,000nm at 20kts quoted by DNC would meet this requirement. For good seakeeping the ship would have `Tribal’ class bows and the `J’ class bridge, which had proven quite satisfactory. She would be stabilised for long-range anti-aircraft accuracy. The main battery would be two twin dual-purpose 4.7in. Controller asked for a sketch of a ship with the desirable close-range battery (four twin Bofors, six Oerlikons), but for comparison he soon also asked for a version with a twin 4in gun in place of two of the Bofors, and for one with eight Oerlikons but no Bofors at all. The ship would also have a depth-charge battery capable of firing ten-charge patterns (ie four throwers).
A sketch design was submitted to the Board in September. Not only did the destroyer officers prefer having both twin mounts forward, that was also the only way to accommodate the very heavy close-range battery. The two mounts were unusually widely spaced (and widely spaced from the bridge) to give generous after arcs. It was unacceptable to devote one of the mounts to fire starshell, so the sketch design showed two starshell mortars (and two Oerlikons) on a midships platform. Alternatives were to modify some of the Bofors guns to fire starshell, or to place a single 4in gun on the platform (as was actually done). Diesel generator capacity was increased so that the ship could fire her power-operated guns even in harbour, with boilers cold. Compared to DNC’s most recent sketch design, this one was somewhat larger (2,280 tons vs 2,250 tons) with a more powerful modified `L’-class plant producing 50,000 SHP rather than 48,000 SHP (for 31.5kts deep, half a knot less than Controller had wanted). She would have 20 per cent better endurance than the `J’ and `K’ class (but 5 per cent less than the `Q’ class): 4,400nm at 20kts (clean) or 7,700nm at 12kts. As in the recent past, above-water `peace tanks’ were rejected as a way of providing the desired endurance.
The Board approved the sketch and the Staff Requirements on 9 October, but the design was still controversial. First Sea Lord accepted it `in deference to professional opinion’ but feared that so large a ship could not be built in sufficient numbers. Ultimately the Royal Navy found itself adopting a high-low mix approach, in which big fleet destroyers were built alongside ships of about Emergency size. The 1942 Programme thus included three flotillas of Emergency Destroyers. DNC was surprised that, after all the destroyer officers had favoured concentrating the armament forward, DOD(H) argued for guns firing aft. Two sketch designs showed that any other gun arrangement would require an unacceptably larger ship.
DNO developed a new between-decks mounting, firing 4.5in rather than 4.7in shells (the 4.5in shell was actually heavier, at 55lbs). Mock-ups were inspected at Barrow on 28 August and 20 October 1941. Progress was quick because this was a version of an existing mounting: the prototype tested on board HMS Savage was modified from a spare made for the carrier Illustrious. The guns were to be controlled by a new Mk VI director using a new anti-aircraft computer (Flyplane). The new computer system and its radar (Type 275) in turn demanded more space. Plans called for installing stabilisers, but internal space was very tight. Instead of stabilisers the ships could stow more oil (up to 135 tons, to supplement the usual supply of 700 tons) or the 100 kW diesel generator otherwise located in the engine room. The Transmitting Station (fire control computer space) could be lowered to protect it. Ultimately the stabiliser was omitted from all but two ships, Camperdown and Finisterre. There was some fear that, because she was so much larger than earlier destroyers, the new one would be far less manoeuvrable, but trials at Haslar suggested that she would turn faster and tighter than any previous destroyer except the small `Hunt’. DNC found the results very reassuring, showing that the conscious effort to hold down length had been well justified. As of April 1942 design displacement was 2,285 tons, the growth of 35 tons being accounted for by increased electric power, the use of a 4in starshell gun (immediately abaft the funnel), and provision for Arctic operations. The sixteen large 1942 Fleet Destroyers all received `Battle’ names.
The new destroyer, so much larger than earlier ones, attracted strong criticism from the fleet, even from the commander of the Home Fleet destroyers. Many argued that the ships were defensively armed, and that they were too weak compared to US destroyers of similar size. Given this sentiment, in mid-1942 the Future Building Committee decided that in future ships of this type the 4in starshell gun would be replaced with a standard 55° 4.5in gun, which could be considered part of the primary armament as well as a starshell gun. Weight compensation would be the removal of one twin Bofors and one Oerlikon. This change was incorporated in the 1943 `Battle’ class.
By the time the ships were being completed more powerful close-range anti-aircraft guns were badly wanted. In April 1945 the Oerlikons on the wings of the deck below the bridge wings were ordered replaced by single power-worked 2pdr Mk XVI* (single power-worked 40mm Mk VII were rejected as causing too much congestion). In June 1945 C-in-C Pacific Fleet asked that the 4in gun be replaced by two single Bofors. Initially ships received hand-worked Army-type Bofors (Mk III LS); plans called for providing gyro gunsights (equivalent to the US Mk 14) for ships completing after September 1945, and power-worked Mk VII mounts for ships completing after December 1945. The typical early post-war battery included six single Bofors: one forward of the bridge on B gun deck, two in the bridge wings, two replacing the 4in gun, and one on the quarterdeck (replaced on modernisation by a single Squid). This was in addition to four twin Bofors: two on the structure between the two sets of torpedo tubes and two on the after deckhouse, for a total of fourteen 40mm guns (the two midships twins were removed on modernisation). Only five ships (Armada, Barfleur, Camperdown, Hogue and Trafalgar) ever had the 4in gun. As flares were still desirable for precise night firing, ships eventually had a medium-range rocket flare launcher which could be mounted on the side of a gun mount.